#include "decode_udp.h"

#define UDP_GET_LEN(udp_hdr) ((uint16_t)ntohs((udp_hdr)->udp_len))
#define UDP_GET_SRC_PORT(udp_hdr) ((uint16_t)ntohs((udp_hdr)->udp_src_port))
#define UDP_GET_DST_PORT(udp_hdr) ((uint16_t)ntohs((udp_hdr)->udp_dst_port))

int decode_udp(udp_info_t *packet, const uint8_t *data, uint32_t len)
{
    if (len < UDP_HEADER_LEN)
    {
        LOG_ERROR("Parser UDP Header: packet length too small %d", len);
        return -1;
    }

    packet->hdr = (udp_header_t *)data;
    // 检查 UDP header len
    if (len < UDP_GET_LEN(packet->hdr))
    {
        LOG_ERROR("Parser UDP Header: UDP packet too small %d", len);
        return -1;
    }

    // 检查 UDP header len
    if (len != UDP_GET_LEN(packet->hdr))
    {
        LOG_ERROR("Parser UDP Header: invalid UDP header length %d", UDP_GET_LEN(packet->hdr));
        return -1;
    }

    packet->src_port = UDP_GET_SRC_PORT(packet->hdr);
    packet->dst_port = UDP_GET_DST_PORT(packet->hdr);

    packet->hdr_len = UDP_HEADER_LEN;
    packet->payload = (uint8_t *)data + UDP_HEADER_LEN;
    packet->payload_len = len - UDP_HEADER_LEN;

    return 0;
}

int dump_udp_info(udp_info_t *packet, char *buff, size_t size)
{
    return snprintf(buff, size,
                    "{\"src_port\":%u,\"dst_port\":%u,\"hdr_len\":%u,\"data_len\":%u}",
                    packet->src_port,
                    packet->dst_port,
                    packet->hdr_len,
                    packet->payload_len);
}